1. Field of the Invention
This invention relates to a signal processing apparatus. In particular, the invention is directed to such a signal processing apparatus having a continuously variable linear voltage controlled oscillator therein.
2. Description of the Prior Art
Voltage controlled oscillators are well known in the prior art. Such an oscillator will accept an analog voltage input signal over some full-scale operating range and generate an output frequency which is linearly proportional to the amplitude of the analog voltage signal. Such oscillators have found many applications where the ratio of the maximum to the minimum analog voltage input signal amplitude is about 10:1.
However, once this ratio is exceeded, the output frequency is no longer linearly proportional to the analog input signal and becomes distorted and unreliable. Compensation for such non-linearity may be made using non-linear amplification circuitry. However, such circuitry is relatively sophisticated, bulky and expensive.